Function Blocks
ALT Alternator Function Block
58 HC900 Hybrid Control Designer Function Block Reference Guide Revision 11
2/07
FOFO Uses the sum of the 16 inputs that are set to ON to determine the required demand for outputs.
The output order is managed in a First ON/First OFF basis (FOFO).
If 3 Inputs are ON (no mapping), the Alternator sequence changes (first one in the list moves to
the end of the list) as the inputs turn OFF or, when there is a request for Advance (see Activate
Advance).
If an input pin is set to “not available”, then that output is forced to OFF and the next available
output is turned ON. If the previously bypassed output later becomes enabled, then it will not
be used until the demand increases.
FIXED Uses the sum of the 16 inputs that are set to ON to determine the required demand for outputs.
The output order is managed in a First ON/First OFF basis (FOFO).
If the Inputs selected are 1, 2, 3, 4 and you map a fixed sequence 4, 2, 3, 1 the sequence will
not change unless you select the Advance feature (see Activate Advance).
It takes a direct command (OFF to ON signal) before the output order map rotates to
the 2, 3, 1, 4 sequence.
If an output pin is not available then that output is forced OFF and the next available output in
the mapping order is turned ON. If the previously bypassed output later becomes enabled, then
it will not be used until the demand increases.
Activate advance
Used with all styles except Direct. If you select “Activate Advance” (click on box on General tab to select),
an OFF to ON transition of the ^ADV Input pin will rotate the output order sequence. Make before Break
selection determines how this is done for Rotary and FOFO only.
Make before break
This feature works on input demand and with the Advance input, it is available for Fixed, Rotary and
FOFO styles.
When the ALT function block receives an Advance input (^ADV pin) and Make before Break is selected
(click on box on General tab to select) the next output in the sequence is activated before deactivating an
output. When the selection box on the General tab is not selected (Break before Make) the output is
removed before advancing the sequence and activating the next output.
The ON and OFF Delay Timers are used with this feature. See next figure.
OFF
Delay
ON
Delay
ON
Delay
ON
Delay
OFF
Delay
ON
Delay
OFF
Delay
ON
OFF
ON
OFF
ON
OFF
ON
OFF
OUTPUT 1
OUTPUT 2
OUTPUT 3
OUTPUT 4
2 outputs
requested
Advance
occurs and
MBB* is set
Advance
occurs and
BBM** is set
* MBB - Make before Break
** BBM - Break before Make
*** When an output is in use and it becomes disabled or fails, the
BBM feature is used to turn on the next available output
2 outputs
requested
and one of
them is
disabled
(or fails)***
3 outputs
requestd
with #3
output still
disabled
initially
no outputs
requested
ON
Delay
ON
Delay
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